A multivariate statistical analysis on variables affecting inferior alveolar nerve damage during third molar surgery

Key Points IAN exposure during third molar surgery cannot be considered a 'warning sign' of nerve damage. The crown luxation should preferably be performed in a direction ipsilateral to the IAN running. Difficult surgeries, multi-rooted teeth and changes in IAN running in relation to tooth roots are real predictors of IAN damage. Aim The risk factors associated with inferior alveolar nerve damage during third molar surgery were investigated. Material and methods Surgeries performed during a period of 50 months by a single expert surgeon were reviewed. Only those surgeries that met the selected inclusion criteria were considered for this study. The following tests were applied for the statistical analysis: the Kolmogorov-Smirnov test, the principal components analysis, the Mann-Whitney U test, the two-tailed exact Fisher test and the Bonferroni sequential correction. Results The surgical difficulty index, multi-rooted third molars and changes in the inferior alveolar nerve running in relation to the tooth roots are predictors of nerve damage. Conclusions Computed tomography is mandatory when the nerve is superimposed on the tooth root on the ortopantomography. Scientific rationale for study Lower third molar extraction is one of the most common procedures in oral and maxillofacial surgery, and it is burdened by the risk of inferior alveolar nerve damage. Understanding which factors are able to predict this complication is therefore essential in correctly programming surgery. Principal findings Surgical difficulty index, multi-rooted third molars and changes in inferior alveolar nerve running in relation to the tooth roots are predictors of nerve damage. Practical implications If, on the orthopantomography, the nerve is superimposed on the tooth root, a computed tomography is mandatory to define all of these variables.